Factors affecting the germination of bulblets of bulbous bluegrass, Poa bulbosa

A study was made of the effect of germination temperature, prechilling and potassium nitrate on the germination of fresh and old bulblets of Poa bulbosa; and of the effect of storage temperature on after-ripening and on longevity of the bulblets. Bulblets approximately 1 month old germinated better at 5 degrees C than at 10 degrees or 20 degrees C constant temperatures. and better with potassium nitrate than with water. Bulblets approximately 4 months old also germinated better at 5 degrees C than at 10 degrees or 20 degrees C. Germination at a temperature alternation of 5 degrees to 15 degrees was faster than at a constant temperature of 5 degrees, but complete germination of the viable bulblets was obtained only by prechilling the bulblets at 5 degrees for 7 or 14 days followed by germination at 10 degrees. As bulblets aged they were tolerant of higher germination temperatures. Bulblets approximately 2 years and 4 years old germinated faster at 20 degrees C than at lower temperatures, but final germination was comparable at 10 degrees. The 2-year-old bulblets required 49 days for completion of germination at 5 degrees. Bulblets having a moisture content of approximately 13% stored in sealed containers at 30 degrees, 20 degrees, 10 degrees, 2 degrees, and -10 degrees C and in unsealed storage at room temperature showed a difference in longevity and in response to the germination temperature. When stored at room temperature, the bulblets after-ripened so that after 10 months' storage they germinated equally well at 5 degrees, 10 degrees, and 20 degrees, but they had fallen in viability after 25 months storage. Bulblets stored at 10 degrees or at 2 degrees showed no appreciable loss of viability in 25 months and maximum germination was obtained at 5 degrees and at 10 degrees but not at 20 degrees. Bulblets stored at -10 degrees became more resistant to the germination conditions tried so that maximum germination was not obtained.